1. Field of the Invention
This present invention relates to medical and scientific measuring devices, and more particularly to a template for precisely and efficiently localizing a lesion of the breast from mammogram results.
2. Description of the Related Art
Mammography has been shown to be the most sensitive and most reliable method to detect breast cancer. Mammograms are generally taken in two non-orthogonal projections for each breast. The “cranial caudal” (CC) projection is taken with the breast being compressed in superior to inferior orientation (vertically) with the x ray tube located in the superior aspect of the breast. The second projection is the “medial lateral oblique” (MLO) projection taken at 45 degree from the horizontal projection with the x ray tube shooting from medial towards lateral but in a 45 degree oblique orientation. This is done because this view maximizes the amount of breast tissue that can be included on the image. The 90-degree orthogonal view of “medial lateral” (ML) is generally not being used because this view cannot image the axillary portion of the breast.
Most physicians divide the breast into 4 quadrants with nipple being the origin of the axes: upper inner quadrant (UIQ), lower inner quadrant (LIQ), upper outer quadrant (UOQ) and lower outer quadrant (LOQ). Because of the non-orthogonal projections of the mammogram views, it could be difficult for the physicians and technologists to precisely localize a lesion (calcification, nodule, or mass) that is seen on the mammogram views. For instance, a lesion of the right breast that is seen lateral to the nipple on the CC view and is above the nipple on the MLO view would often be thought to be located in the upper outer quadrant can actually be in the lower outer quadrant depending upon how far it is located from the nipple.
Another system is describing the location of a lesion is a radial system. The breast is divided into parts like the face of a clock with the nipple being the center of the clock. The location of the lesion is given in terms of the clock position. For example, a lesion can be described as located in the 2 O'clock position and 4 cm away from the nipple. However, the same problem in translating the location of the lesion on the mammogram into radial coordinate exists as the Cartesian coordinate system because of the obliquity of the MLO view.
The ambiguity of the localizing lesion on the bases of mammogram can be a significant problem when the physician or technician needs to find the lesion on ultrasound. In general, the ultrasound technologists need to scan the entire half of the breast and still have problem finding the lesion. This is extremely time consuming and expensive. Often times it is difficult to be sure that a lesion seen on ultrasound is the same lesion seen on mammogram. It would be of grave consequences if a cancer seen on mammogram is called benign because ultrasound found a benign tumor (cyst or fibroadenoma) located close to the cancer. It certainly would increase the level of confidence of ultrasound findings if lesion could be more precisely localized.
U.S. Pat. No. 4,279,259, issued to D.C. Lee et al, discloses what is referred to in that patent as a “mammometer” for measuring breasts and for providing a doctor with a means for placing reference marks on the patient's breast. These marks are made by a device that uses arcs for making these determinations. The main purpose of this device is to measure the size of the women's breasts for determination of the type and size of breast implants or prosthesis. It cannot be used in conjunction with mammograms in localizing lesions within the breast because it does not take into account of how the mammograms are being performed or the direction of the x-ray beam. The Lee device utilizes a series of arcs that follow the contours of the breast. It does not utilize axes that reference how the x-ray beams are directed. The device, therefore, cannot be used to localize a lesion within the women's breast.